Adaptive serial and parallel mixed interference cancellation method

Abstract

The present invention relates to a CDMA system, which, in part, uses serial and parallel interference cancellation methods to overcome disadvantages of a method of detecting single user, and comprises a feedback loops for providing reproduced signals to respective inputs of detectors, and a means for controlling an operation for the detectors to attribute to interference cancellation process. The detectors to contribute to interference cancellation process can be also selected group by group. It is used to switch off only detectors contributing to interference cancellation process in progress and detectors contributing to previous interference cancellation, providing a adaptive serial and parallel mixed interference cancellation method for increasing performance and capacity of the CDMA system.

What is claimed is: 
     
       1. An adaptive serial and parallel mixed interference cancellation method, comprising the steps of: storing a received signal in a buffer via a low pass filter;   receiving a buffer signal output from said buffer at a plurality of detectors;   selecting arbitrary ones of decision signals output from the plurality of detectors in a selection controller;   closing a switch corresponding to a selected signal selected in said selection controller and transmitting said selected signal with a (+1,-1) binary data signal through a signum function to a processor;   recovering said (+1,-1) binary data signal at said processor;   reproducing a baseband signal of the recovered signal during said step of; and   feeding the reproduced baseband signal to an address via feedback loops and adding said reproduced baseband signal at an adder to remove the reproduced baseband signal from the received signal to thereby produce new signals.   
     
     
       2. The adaptive serial and parallel mixed interference cancellation method of claim 1, further comprising the steps of selecting detectors by one of group by group and one by one, thereby attributing to the interference cancellation process in progress. 
     
     
       3. The adaptive serial and parallel mixed interference cancellation method of claim 1, wherein said step of recovering said (+1,-1) binary data signal comprises recovering said (+1,-1) binary data signal using a control signal. 
     
     
       4. The adaptive serial and parallel mixed interference cancellation method of claim 1, further comprising the steps of updating estimation values of said detectors based on the reproduced signal and the new signals whose interference noise components are cancelled. 
     
     
       5. The adaptive serial and parallel mixed interference cancellation method of claim 4, further comprising the steps of continuing to attribute the updated estimation values to the interference cancellation process and updating the decision values for each production of the new signals even during said steps of receiving a buffer signal and selecting arbitrary ones. 
     
     
       6. The adaptive serial and parallel mixed interference cancellation method of claim 1, wherein said selection controller selects arbitrary number of detectors, and the number of detector selected in said selection controller ranges from one to the total number of the users (K). 
     
     
       7. The adaptive serial and parallel mixed interference cancellation method of claim 1, wherein said closing switches closes the switch corresponding to the detectors selected at the current interference cancellation processing, and does not open them until the final bit decision is made after all the interference cancellation processes are accomplished. 
     
     
       8. The adaptive serial and parallel mixed interference cancellation method of claim 1, wherein said recursive parallel interference cancellation can be accomplished with one stage hardware when the number of detector selected in the interference canceling processing equals to K. 
     
     
       9. An adaptive serial and parallel mixed interference cancellation method, comprising the steps of: storing a received signal in a buffer via a low pass filter;   receiving a buffer signal output from said buffer at a plurality of detectors;   selecting arbitrary ones of decision signals output from the plurality of detectors in a selection controller;   closing a switch corresponding to a selected signal selected in said selection controller and transmitting said selected signal with a (+1,-1) binary data signal through a signum function to a processor;   recovering said (+1,-1) binary data signal at said processor;   reproducing a baseband signal of the recovered signal during said step of feeding the reproduced baseband signal to an address via teedback loops;   adding said reproduced baseband signal at an adder to remove the reproduced baseband signal from the received signal to thereby produce new signals;   updating estimation values of said detectors based on the reproduced signal and the new signals whose interference noise components are cancelled, wherein; and   continuing to attribute the updated estimation values to the interference cancellation process and updating the decision values for each production of the new signals even during said steps of receiving a butter signal and selecting arbitrary ones.